and the code below, I'm blocked forever (on reading from STDIN ?!!) when running it like

$ ./weird.pl sample.txt

whereas

$ ./weird.pl <sample.txt

or

$ cat sample.txt | ./weird.pl

works perfectly OK. I'm trying to make a number of DNS requests in an async manner, controlling the maximum number of open sessions at any time and processing the names of the hosts to be checked in a 'stream-like' fashion.

I have work-arounds, so I'm not looking for alternate solutions, but I'm just trying to understand why this code doesn't work and blocks, apparently when hitting the end of the file given on the command line.

Am I doing something that isn't right or is Perl this time not keeping it's promesses about how files on the command line are processed ...?

Ada Lovelace for the palindrome
Albert Einstein for having smelly feet
Alfred Nobel for his contribution to battlefield science
Burkhard Heim for providing the missing link between science and mysticism
Claude Shannnon for riding a unicycle at night at MIT
Donald Knuth for being such a great organist
Edward Teller for being the template for Dr. Strangelove
Edwin Hubble for pretending to be a pipe-smoking English gentleman
Erwin Schrödinger for cruelty to cats
Hedy Lamarr for weaponizing pianos
Hugh Everett for immortality, especially for cats
Isaac Newton for his occult studies
Kikunae Ikeda for discovering the secrets of soy sauce
Larry Wall for his website
Louis Camille Maillard for discovering why steaks taste good
Marie Curie for the shiny stuff
Nikola Tesla for the cool cars
Paul Dirac for speaking one word per hour when socializing
Richard Feynman for his bongo skills
Robert Oppenheimer for his in-depth knowledge of the Bhagavad Gita
Rusi P Taleyarkhan for Cold Fusion
Sigmund Freud for his Ménage ā trois
Theodor W Adorno for his contribution to the reception of jazz
Wilhelm Röntgen for the foundations of body scanners
Yulii Borisovich Khariton for the Tsar Bomba
Other (please explain why)